DTC P0420: Catalyst System Efficiency Below Threshold (Bank 1) [08/2014 - 11/2016]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
5. Read the DTCs.

   Powertrain > Engine > Trouble Codes 

   Result

   Result	Proceed to
   DTC P0420 is output	A
   DTC P0420 and other DTCs are output	B

   HINT: 

   If any DTCs other than P0420 are output, troubleshoot those DTCs first.

Result: 

B 

Refer to  DIAGNOSTIC TROUBLE CODE CHART [08/2014 - 11/2015]  or  DIAGNOSTIC TROUBLE CODE CHART [11/2015 - 11/2016] 

Result: 

A 

See step  2

1. Connect the Techstream to the DLC3.
2. Start the engine and warm it up.
3. Turn the Techstream on.
4. Run the engine at an engine speed of 2500 rpm for approximately 90 seconds.
5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / GAS AF Control / AFS Voltage B1S1 and O2S B1S2.

   Powertrain > Engine > Active Test 

   Active Test Display
   Control the Injection Volume for A/F Sensor

   Data List Display
   AFS Voltage B1S1
   O2S B1S2

6. Perform the Active Test operation with the engine idling (press the 12.5% or -12.5% button to change the fuel injection volume).
7. Monitor the voltage outputs of the air fuel ratio sensor and heated oxygen sensor (AFS Voltage B1S1 and O2S B1S2) displayed on the Techstream.

   HINT: 

   • The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
   • Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
   • The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
   • If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

   Standard

   Techstream Display (Sensor)	Injection Volume	Status	Voltage
   AFS Voltage B1S1 (Air fuel ratio)	12.5%	Rich	Below 3.1 V
   	-12.5%	Lean	Higher than 3.4 V
   O2S B1S2 (Heated oxygen)	12.5%	Rich	Higher than 0.55 V
   	-12.5%	Lean	Below 0.4 V

   Result

   Status AFS Voltage B1S1	Status O2S B1S2	Actual air fuel ratio, air fuel ratio sensor and heated oxygen sensor condition	Misfire	Main Suspected Trouble Area	Proceed to
   Lean/Rich	Lean/Rich	Normal	-	Three-way catalytic converter Gas leak from exhaust system	A
   Lean	Lean/Rich	Air fuel ratio sensor malfunction	-	Air fuel ratio sensor	B
   Rich	Lean/Rich	Air fuel ratio sensor malfunction	-	Air fuel ratio sensor
   Lean/Rich	Lean	Heated oxygen sensor malfunction	-	Heated oxygen sensor Gas leak from exhaust system	C
   Lean/Rich	Rich	Heated oxygen sensor malfunction	-	Heated oxygen sensor Gas leak from exhaust system
   Lean	Lean	Actual air fuel ratio lean	May occur	Extremely lean actual air fuel ratio Gas leak from exhaust system	D
   Rich	Rich	Actual air fuel ratio rich	-	Extremely rich actual air fuel ratio Gas leak from exhaust system

   Lean: During Control the Injection Volume for A/F Sensor Active Test, the air fuel ratio sensor output voltage (AFS Voltage B1S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S B1S2) is consistently below 0.4 V.

   Rich: During Control the Injection Volume for A/F Sensor Active Test, AFS Voltage B1S1 is consistently below 3.1 V, and O2S B1S2 is consistently higher than 0.55 V.

   Lean/Rich: During Control the Injection Volume for A/F Sensor Active Test, the output voltage of the air fuel ratio sensor and heated oxygen sensor alternate correctly.

   HINT: 

   Refer to "Data List / Active Test" [AFS Voltage B1S1 and B1S2].

   Refer to DATA LIST / ACTIVE TEST [08/2014 - 11/2015] or DATA LIST / ACTIVE TEST [11/2015 - 11/2016]

Result: 

B 

See step  4

Result: 

C 

See step  5

Result: 

D 

See step  7

Result: 

A 

See step  3

1. Check for exhaust gas leaks.

   OK

   No gas leaks.

Result: 

OK 

See step  11

Result: 

NG 

See step  9

Refer to REMOVAL [12/2013 - ]

HINT: 

Perform "Inspection After Repair" after replacing the air fuel ratio sensor.

Refer to INITIALIZATION [12/2013 - ]

NEXT 

See step  10

1. Check for exhaust gas leaks.

   OK

   No gas leaks.

Result: 

NG 

See step  9

Result: 

OK 

See step  6

Refer to REMOVAL [12/2013 - ]

HINT: 

Perform "Inspection After Repair" after replacing the heated oxygen sensor.

Refer to INITIALIZATION [12/2013 - ]

NEXT 

See step  10

1. Check the exhaust gas leaks.

   OK

   No gas leaks.

Result: 

NG 

See step  9

Result: 

OK 

See step  8

1. Check the cause of extremely rich or lean actual air fuel ratio, referring to the DTC P0171 and P0172 Inspection Procedure.

   Refer to DTC P0171: System Too Lean (Bank 1); DTC P0172: System Too Rich (Bank 1) [12/2013 - 11/2016]

NEXT 

See step  10

Perform "Inspection After Repair" after repairing or replacing the exhaust system.

Refer to INITIALIZATION [12/2013 - ]

NEXT 

See step  10

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear the DTCs.

   Refer to DTC CHECK / CLEAR [12/2013 - 11/2016]

   Powertrain > Engine > Clear DTCs 

5. Turn the ignition switch off and wait for at least 30 seconds.
6. Start the engine.
7. Turn the Techstream on.
8. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
10. Read the DTCs.

    Powertrain > Engine > Trouble Codes 

    Result

    Result	Proceed to
    DTC P0420 is output	A
    DTCs are not output	B

Result: 

B 

END 

Result: 

A 

See step  11

HINT: 

Confirm the replacement parts, referring to the illustration in the Catalyst Location.

1. Replace the front exhaust pipe assembly (TWC: Front catalyst).

   Refer to COMPONENTS [12/2013 - 11/2016]

2. Replace the center exhaust pipe assembly (TWC: Rear catalyst).

   Refer to COMPONENTS [12/2013 - 11/2016]